A case of losartan-induced severe hyponatremia

Abstract

This case report outlines a very rare case of losartan-induced severe hyponatremia in a 73-year-old type 2 diabetic patient. The patient was initiated with 50 mg daily oral losartan monotherapy for newly diagnosed moderate hypertension. After 3.5 months of taking the drug, he presented to the emergency department in a drowsy state with severe generalized weakness and occasional palpitations. He was a known diabetic for the last 3 years and well controlled by oral metformin alone. On examination, his serum sodium level was found to be 123 meq/L. There were no evidences of any other possible metabolic, infective, organic or other pathologic causes giving rise to that condition, except losartan itself. De-challenge was done and he was treated vigorously resulting in reversal of the diseased state. Naranjo adverse drug reaction probability scale suggested that it was “probable” that oral losartan was responsible for the development of severe hyponatremia in this patient.

Severe hyponatremia due to trimethoprim-sulfamethoxazole-induced SIADH

“… 14 , 15 Hyperkalemia has been reported to occur in up to 10% of patients taking TMP-SMX and spironolactone concurrently. 10 TMP-SMX was probably the cause of hyponatremia in our patient, based on Naranjo’s probability scale. 16 Providers need to consider drug interactions between TMP-SMX and spironolactone since both drugs are readily available and routinely prescribed.…”

“…This patient had other conditions known to cause hyponatremia, including hypothyroidism and her prescription drugs (losartan, gabapentin, amiodarone, hydrocodone). 10 – 12 When hypothyroid patients develop hyponatremia, they usually suffer from severe symptoms or have myxedema. 13 Although our patient’s TSH level was elevated, she was asymptomatic, suggesting hypothyroidism was not the cause of her severe hyponatremia.…”

Associations Between Antihypertensive Medications and Severe Hyponatremia: A Swedish Population–Based Case–Control Study

“…ARBs were developed as a more specific drug blocking the angiotensin II receptor. ARBs have been associated with severe hyponatremia in some cases ( 21 , 26 ). It has been speculated that blocking the angiotensin I receptor leads to an angiotensin II–mediated decrease in renal tubular sodium reabsorption resulting in hyponatremia ( 26 ).…”

“…ARBs have been associated with severe hyponatremia in some cases ( 21 , 26 ). It has been speculated that blocking the angiotensin I receptor leads to an angiotensin II–mediated decrease in renal tubular sodium reabsorption resulting in hyponatremia ( 26 ). However, most cases of ARB-induced severe hyponatremia seemed to have occurred in patients on ARBs in combination with a thiazide diuretic ( 38 ).…”

“…Thiazide diuretics are well-known to induce hyponatremia ( 6 ), but whether hyponatremia can be induced by the other 4 major drug classes is more controversial ( 8 ). Mostly case reports or smaller observational studies have described hyponatremia induced by CCBs ( 19-21 ), BBs ( 21 ), ACEIs ( 21-25 ), and ARBs ( 21 , 26 ). Due to the considerable prescription of these drugs, even a rare adverse reaction may have considerable clinical implications.…”